As an electro-photographic type image forming apparatus, a printer including a photosensitive body and a developing cartridge configured to supply toner to the photosensitive body is known.
A conventional printer is provided with a detection device for detecting information of the developing cartridge assembled therein, for example, for detecting whether or not the cartridge is a brand new cartridge.
Japanese Patent Application Publication No. 2007-79284 discloses a detection structure having a detection projection as the detection device. The detection projection is made from an electrically conductive resin and is provided at a side surface of the developing cartridge. The projection is in abutment with an actuator in a main casing of the printer.
The detection structure is covered by a gear cover, and is irreversibly displaceable from a new cartridge position to an old cartridge position. The detection projection is accommodated in the gear cover in case of the new cartridge position. Upon receipt of a driving force from a drive source in the main casing, the detection projection is exposed to an outside through an opening of the gear cover while the detection structure is displaced from the new cartridge position to the old cartridge position.